Insect pests are a major factor in the loss of the world's agricultural crops. For example, armyworm feeding, black cutworm damage, or European corn borer damage can be economically devastating to agricultural producers. Insect pest-related crop loss from European corn borer attacks on field and sweet corn alone has reached about one billion dollars a year in damage and control expenses.
Traditionally, the primary method for controlling insect pest populations is the application of broad-spectrum chemical insecticides. However, consumers and government regulators alike are becoming increasingly concerned with the environmental hazards associated with the production and use of synthetic chemical pesticides. Because of such concerns, regulators have banned or limited the use of some of the more hazardous pesticides. Thus, there is substantial interest in developing alternative pesticides.
Biological control of insect pests of agricultural significance using a microbial agent, such as fungi, bacteria, or another species of insect affords an environmentally friendly and commercially attractive alternative to synthetic chemical pesticides. Generally speaking, the use of biopesticides presents a lower risk of pollution and environmental hazards, and biopesticides provide greater target specificity than is characteristic of traditional broad-spectrum chemical insecticides. In addition, biopesticides often cost less to produce and thus improve economic yield for a wide variety of crops.
Certain species of microorganisms of the genus Bacillus are known to possess pesticidal activity against a broad range of insect pests including Lepidoptera, Diptera, Coleoptera, Hemiptera, and others. Bacillus thuringiensis (Bt) and Bacillus papilliae are among the most successful biocontrol agents discovered to date. Insect pathogenicity has also been attributed to strains of B. larvae, B. lentimorbus, B. sphaericus and B. cereus. Microbial insecticides, particularly those obtained from Bacillus strains, have played an important role in agriculture as alternatives to chemical pest control.
Crop plants have been developed with enhanced insect resistance by genetically engineering crop plants to produce pesticidal proteins from Bacillus. These genetically engineered crops are now widely used in American agriculture and have provided producers with an environmentally friendly alternative to traditional insect-control methods. While they have proven to be very successful commercially, these genetically engineered, insect-resistant crop plants typically provide resistance to only a narrow range of economically important pests. Some insects have developed resistance to some insecticidal polypeptides in these genetically engineered crops.
Accordingly, there remains a need for new pesticidal proteins with a broader range of insecticidal activity against insect pests, e.g., toxins which are active against a greater variety of insects from the order Lepidoptera, Coleoptera, Hemiptera, and others. In addition, there remains a need for biopesticides having improved insecticidal activity, and activity against insects that have developed resistance to existing pesticides and pesticidal proteins.